Field of Invention
Various embodiments of the present invention relate to mobile communication, and more particularly, to a method and apparatus for transmitting and receiving data via a mobile channel.
Description of Related Art
Compared to the late 1990s when a wireless LAN card had to be inserted into a notebook to be used, nowadays, various smart apparatuses such as notebooks, PCs, smart phones, and smart pads are manufactured with a wireless LAN mounted thereon in the first place. Wireless LANs are being used in various apparatuses for various purposes, for example, internet can be accessed via a wireless LAN, and various services such as transmitting files and data between apparatuses, and high resolution video streaming are being used based on a wireless LAN in daily lives. Recently, usage of wireless LANs are being extended to areas that would have been unimaginable in the past such as keeping safety in homes, and contributing to reducing electricity costs for customers in connection with electricity companies by adjusting electronic devices not only in homes but also outside homes.
The IEEE 802.11ac standard enables gigabyte transmission rates in 5 GHz bands based on wireless LANs. Besides ultraspeed transmissions, various service scenarios have become possible using wireless LANs. Furthermore, standardization is actively in the way for the IEEE 802.11 ah and IEEE 802.11af technologies which use a frequency band of or less than 1 GHz, and which shares a frequency band for TVs thereby extending the wireless LAN coverage. Besides the aforementioned, standardizing the IEEE 802.11ai for reducing access time in congested areas is underway.
The IEEE 802.11af is a technology where a wireless LAN shares a TV idle band based on a database. It uses the IEEE 802.11ac PHY (physical layer) of 5 GHz by down clocking. The IEEE 802.11af is significantly influenced by frequency regulations regarding a TV idle band, and recently the US FCC announced a reverse auction regarding a TV idle band, and its results that will come out in 2015 which is being watched with keen interest.
The IEEE 802.11ah enables broadband wireless LAN services using the increase in radio coverage based on frequency band characteristics of or less than 1 GHz. Furthermore, it supports a plurality of low power sensors operating in power saving modes, and may be used in cellular offloading. Preamble and beacon signals have been designed to be suitable for such service application areas, and TIMs (Traffic Indication MAP) have also been designed to have layered structures.
The IEEE 802.11ai is a MAC technology for reducing wireless LAN access time. It reduces the access time under congested conditions by filtering a probe response in active scanning, and reduces the access time by designing new discovery frames and simplifying security levels.